Titanium(IV) hydride

Last updated
Titanium(IV) hydride
Titanium(IV)-hydride, 2D.png
Systematic IUPAC name
Titanium(IV) hydride
Other names
Titanium tetrahydride
3D model (JSmol)
ECHA InfoCard 100.035.414 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 238-972-5
PubChem CID
UN number 1871
  • InChI=1S/Ti.4H
  • [TiH4]
Molar mass 51.899 g/mol
AppearanceColourless gas
Related compounds
Other anions
Titanium(IV) fluoride
Titanium(IV) chloride
Titanium(IV) bromide
Titanium(IV) iodide
Other cations
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Titanium(IV) hydride (systematically named titanium tetrahydride) is an inorganic compound with the empirical chemical formula TiH
. It has not yet been obtained in bulk, hence its bulk properties remain unknown. However, molecular titanium(IV) hydride has been isolated in solid gas matrices. The molecular form is a colourless gas, and very unstable toward thermal decomposition. As such the compound is not well characterised, although many of its properties have been calculated via computational chemistry.


Synthesis and stability

Titanium(IV) hydride was first produced in 1963 by the photodissociation of mixtures of TiCl4 and H2, followed by immediate mass spectrometry. [1] Rapid analysis was required as titanium(IV) hydride is extremely unstable. Computational analysis of TiH4 has given a theoretical bond dissociation energy (relative to M+4H) of 132 kcal/mole. [2] As the dissociation energy of H2 is 104 kcal/mole the instability of TiH4 can be expected to be thermodynamic; with it dissociating to metallic titanium and hydrogen:

TiH4 → Ti + 2 H2 (76 kcal/mole)

TiH4, along with other unstable molecular titanium hydrides, (TiH, TiH2, TiH3 and polymeric species) has been isolated at low temperature following laser ablation of titanium. [3]


It is suspected that within solid titanium(IV) hydride, the molecules form aggregations (polymers), being connected by covalent bonds. [4] Calculations suggest that TiH4 is prone to dimerisation. [3] This largely attributed to the electron deficiency of the monomer and the small size of the hydride ligands; which allows dimerisation to take place with a very low energy barrier as there is a negligible increase in inter-ligand repulsion.

The dimer is a calculated to be a fluxional molecule rapidly inter-converting between a number of forms, all of which display bridging hydrogens. [4] This is an example of three-center two-electron bonding.

Monomeric titanium(IV) hydride is the simplest transition metal molecule that displays sd3 orbital hybridisation. [5]

Related Research Articles

A Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, is a catalyst used in the synthesis of polymers of 1-alkenes (alpha-olefins). Two broad classes of Ziegler–Natta catalysts are employed, distinguished by their solubility:

<span class="mw-page-title-main">Hydride</span> Molecule with a hydrogen bound to a more electropositive element or group

In chemistry, a hydride is formally the anion of hydrogen (H), a hydrogen atom with two electrons. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.

<span class="mw-page-title-main">Diborane</span> Chemical compound

Diborane(6), commonly known as diborane, is the chemical compound with the formula B2H6. It is a toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Given its simple formula, borane is a fundamental boron compound. It has attracted wide attention for its electronic structure. Several of its derivatives are useful reagents.

Borderline hydrides typically refer to hydrides formed of hydrogen and elements of the periodic table in group 11 and group 12 and indium (In) and thallium (Tl). These compounds have properties intermediate between covalent hydrides and saline hydrides. Hydrides are chemical compounds that contain a metal and hydrogen acting as a negative ion.

<span class="mw-page-title-main">Aluminium hydride</span> Chemical compound

Aluminium hydride is an inorganic compound with the formula AlH3. Alane and its derivatives are part of a family of common reducing reagents in organic synthesis based around group 13 hydrides. In solution—typically in etherial solvents such tetrahydrofuran or diethyl ether—aluminium hydride forms complexes with Lewis bases, and reacts selectively with particular organic functional groups, and although it is not a reagent of choice, it can react with carbon-carbon multiple bonds. Given its density, and with hydrogen content on the order of 10% by weight, some forms of alane are, as of 2016, active candidates for storing hydrogen and so for power generation in fuel cell applications, including electric vehicles. As of 2006 it was noted that further research was required to identify an efficient, economical way to reverse the process, regenerating alane from spent aluminium product.

<span class="mw-page-title-main">Digallane</span> Chemical compound

Digallane is an inorganic compound with the chemical formula GaH2(H)2GaH2. It is the dimer of the monomeric compound gallane. The eventual preparation of the pure compound, reported in 1989, was hailed as a "tour de force." Digallane had been reported as early as 1941 by Wiberg; however, this claim could not be verified by later work by Greenwood and others. This compound is a colorless gas that decomposes above 0 °C.

Transition metal hydrides are chemical compounds containing a transition metal bonded to hydrogen. Most transition metals form hydride complexes and some are significant in various catalytic and synthetic reactions. The term "hydride" is used loosely: some of them are acidic (e.g., H2Fe(CO)4), whereas some others are hydridic, having H-like character (e.g., ZnH2).

<span class="mw-page-title-main">Beryllium hydride</span> Chemical compound

Beryllium hydride is an inorganic compound with the chemical formula n. This alkaline earth hydride is a colourless solid that is insoluble in solvents that do not decompose it. Unlike the ionically bonded hydrides of the heavier Group 2 elements, beryllium hydride is covalently bonded.

Zinc hydride is an inorganic compound with the chemical formula ZnH2. It is a white, odourless solid which slowly decomposes into its elements at room temperature; despite this it is the most stable of the binary first row transition metal hydrides. A variety of coordination compounds containing Zn–H bonds are used as reducing agents, however ZnH2 itself has no common applications.

Boron monofluoride or fluoroborylene is a chemical compound with the formula BF, one atom of boron and one of fluorine. It is an unstable gas, but it is a stable ligand on transition metals, in the same way as carbon monoxide. It is a subhalide, containing fewer than the normal number of fluorine atoms, compared with boron trifluoride. It can also be called a borylene, as it contains boron with two unshared electrons. BF is isoelectronic with carbon monoxide and dinitrogen; each molecule has 14 electrons.

Scandium trihydride is an unstable molecular chemical compound with the chemical formula ScH3. It has been formed as one of a number of other molecular scandium hydride products at low temperature using laser ablation and identified by infrared spectroscopy. Scandium trihydride has recently been the subject of Dirac–Hartree–Fock relativistic calculation studies, which investigate the stabilities, geometries, and relative energies of hydrides of the formula MH3, MH2, or MH.

Binary compounds of hydrogen are binary chemical compounds containing just hydrogen and one other chemical element. By convention all binary hydrogen compounds are called hydrides even when the hydrogen atom in it is not an anion. These hydrogen compounds can be grouped into several types.

Cadmium hydride is an inorganic compound with the chemical formula (CdH
. It is a solid, known only as a thermally unstable, insoluble white powder.

<span class="mw-page-title-main">Chromium(I) hydride</span> Chemical compound

Chromium(I) hydride, systematically named chromium hydride, is an inorganic compound with the chemical formula (CrH)
. It occurs naturally in some kinds of stars where it has been detected by its spectrum. However, molecular chromium(I) hydride with the formula CrH has been isolated in solid gas matrices. The molecular hydride is very reactive. As such the compound is not well characterised, although many of its properties have been calculated via computational chemistry.

Chromium(II) hydride, systematically named chromium dihydride and poly­(dihydridochromium) is pale brown solid inorganic compound with the chemical formula (CrH2)n. Although it is thermodynamically unstable toward decomposition at ambient temperatures, it is kinetically metastable.

<span class="mw-page-title-main">Iron(I) hydride</span> Chemical compound

Iron(I) hydride, systematically named iron hydride and poly(hydridoiron) is a solid inorganic compound with the chemical formula (FeH)
(also written ([FeH])
or FeH). It is both thermodynamically and kinetically unstable toward decomposition at ambient temperature, and as such, little is known about its bulk properties.

Iron(II) hydride, systematically named iron dihydride and poly(dihydridoiron) is solid inorganic compound with the chemical formula (FeH
(also written ([FeH
)n or FeH
). ). It is kinetically unstable at ambient temperature, and as such, little is known about its bulk properties. However, it is known as a black, amorphous powder, which was synthesised for the first time in 2014.

Group 14 hydrides are chemical compounds composed of hydrogen atoms and group 14 atoms.

Germyl, trihydridogermanate(1-), trihydrogermanide, trihydridogermyl or according to IUPAC Red Book: germanide is an anion containing germanium bounded with three hydrogens, with formula GeH−3. Germyl is the IUPAC term for the –GeH3 group. For less electropositive elements the bond can be considered covalent rather than ionic as "germanide" indicates. Germanide is the base for germane when it loses a proton.

Hydrogen compounds are compounds containg the element hydrogen. In these compounds, hydrogen can form in the +1 and -1 oxidation states. Hydrogen can form compounds both ionically and in covalent substances. It is a part of many organic compounds such as hydrocarbons as well as water and other organic substances. The H+ ion is often called a proton because it has one proton and no electrons, although the proton does not move freely. Brønsted–Lowry acids are capable of donating H+ ions to bases.


  1. Breisacher, Peter; Siegel, Bernard (5 June 1963). "Formation of Gaseous Titanium(IV) Hydride and Chlorohydrides of Titanium". Journal of the American Chemical Society. 85 (11): 1705–1706. doi:10.1021/ja00894a049.
  2. Hood, Diane M.; Pitzer, Russell M.; Schaefer, Henry F. (1 January 1979). "Electronic structure of homoleptic transition metal hydrides: TiH4, VH4, CrH4, MnH4, FeH4, CoH4, and NiH4". The Journal of Chemical Physics. 71 (2): 705. Bibcode:1979JChPh..71..705H. doi:10.1063/1.438357.
  3. 1 2 Chertihin, George V.; Andrews, Lester (September 1994). "Reactions of laser ablated Ti atoms with hydrogen during condensation in excess argon. Infrared spectra of the TiH, TiH2, TiH3, and TiH4 molecules". Journal of the American Chemical Society. 116 (18): 8322–8327. doi:10.1021/ja00097a045.
  4. 1 2 Webb, Simon P.; Gordon, Mark S. (July 1995). "The dimerization of TiH
    ". Journal of the American Chemical Society. 117 (27): 7195–7201. doi:10.1021/ja00132a020.
  5. Jonas, V.; Boehme, C.; Frenking, G. (1996). "Bent's Rule and the Structure of Transition Metal Compounds". Inorg. Chem. 35 (7): 2097–2099. doi:10.1021/ic951397o.